Digital Image Resolution / ppi → px/mm
Convert Pixels per inch to Pixels per millimeter
Convert linear pixel density between pixels per inch and per metric distance. Convert Pixels per inch (ppi) to Pixels per millimeter (px/mm). Find the formula, worked examples, unit definitions, and practical guidance below.
Reverse: Pixels per millimeter to Pixels per inch →
How to convert pixels per inch to pixels per millimeter
Pixel density relates pixel counts to physical length. Printer dots (DPI) are not necessarily image pixels (PPI); resolution alone cannot determine image dimensions without a pixel count. This tool does not resize images.
Use x for the value in ppi, b for the intermediate value in px/m, and y for the result in px/mm.
px/mm = ppi × 39.37007874015748 ÷ 1000
Worked examples
10 ppi ≈ 0.393700787402 px/mm
Step 1: (10 × 39.3700787402) ≈ 393.700787402 px/m.
Step 2: 393.700787402 ÷ 1000 ≈ 0.393700787402 px/mm.20 ppi ≈ 0.787401574803 px/mm
Step 1: (20 × 39.3700787402) ≈ 787.401574803 px/m.
Step 2: 787.401574803 ÷ 1000 ≈ 0.787401574803 px/mm.
Results are rounded to 12 significant digits. Converting units does not increase the precision of the original measurement. Very large or small values outside JavaScript’s finite numeric range are rejected.
About Pixels per inch
Pixels per inch (ppi) measures digital image resolution under the conventions above. The base value in px/m is (x × 39.3700787402), where x is the numerical value in ppi. Factors shown here are rounded for display; calculations use the stored factor.
About Pixels per millimeter
Pixels per millimeter (px/mm) measures digital image resolution under the conventions above. The base value in px/m is (x × 1000), where x is the numerical value in px/mm. Factors shown here are rounded for display; calculations use the stored factor.
Definitions and sources
For a different quantity or formatting task, see the related other conversion tools.
Pixels per inch to pixels per millimeter reference table
| Pixels per inch (ppi) | Pixels per millimeter (px/mm) |
|---|---|
| 1 | 0.0393700787402 |
| 5 | 0.196850393701 |
| 10 | 0.393700787402 |
| 25 | 0.984251968504 |
| 50 | 1.96850393701 |
| 100 | 3.93700787402 |
| 1000 | 39.3700787402 |
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